Section 2 Coatings

*Corrosion*

2213-2224

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**59**

**Chapter 4**

**Abstract**

Organic-Inorganic Hybrid

Corrosion Protection

*Mayara C. Uvida and Peter Hammer*

(impedance modulus up to 100 GΩ cm2

service life of metallic components.

**1. Introduction**

Coatings for Active and Passive

*Andressa Trentin, Samarah V. Harb, Thiago A.C. de Souza,* 

Organic-inorganic coatings based on poly(methyl methacrylate) (PMMA)-silica and PMMA-cerium oxide hybrids provide effective and active corrosion protection of metallic surfaces. For both hybrid materials, the covalent conjugation of inorganic silica or ceria nanodomains with the PMMA matrix, provided by molecular coupling agents, leads to homogenous and highly cross-linked nanocomposites, which act in the form of coatings as an efficient diffusion barrier. The addition of lithium salts (500–2000 ppm) into PMMA-silica hybrid and optimized ceria fraction in PMMA-cerium oxide coatings results in active corrosion inhibition by the self-healing effect. Results of electrochemical assays of aluminum- and steel-coated samples, performed in a 3.5% NaCl solution, show an excellent corrosion resistance

10-μm-thick passive barrier layer. Time-of-flight secondary ion mass and X-ray photoelectron spectroscopies evidenced the self-healing ability of coatings induced by lithium/cerium ion leaching toward corrosion spots or artificial scratches, which are restored by a protective layer of precipitated phases. Results presented in this book chapter evidence the active role of lithium and cerium species in improving the hybrid structure and providing through self-healing a significantly extended

**Keywords:** anticorrosion coating, organic-inorganic hybrid, passive and active

The development of efficient production techniques of metallic alloys in the late twentieth century formed the basis for the boom of construction, transportation, energy, packaging, and electronic industries [1, 2]. Although extensively used, unprotected alloys are subject to a constant oxidation process, either in contact with humid atmosphere, aqueous, or soil systems, turning them into natural ore [1, 3]. One common approach to prevent or at least delay metallic corrosion is the application of organic coatings as a physical diffusion barrier. A barrier coating in the form of a dense insulating layer acts as a quasi-ideal capacitor, which

protection, corrosion inhibitors, self-healing, AA7075, carbon steel

) and durability (up to 350 days) of the

#### **Chapter 4**
